Overall an Unremarkable Epidemic
Every week the nation's Centers for Disease Control and Prevention, the CDC, publishes a rich set of statistics on the course of the influenza virus in the United States. It has done so for years, so we can both track the current progress of every winter's influenza virus, and compare it to prior years.
The good news is that, as with every other recorded influenza epidemic, this one is ending too, and it is ending now. Very soon the winter epidemic if influenza viral infections will be over.
And so, we are also ending our administration of this winter's influenza vaccine. We are very pleased at the level of protection it offered, and looking over the nation's experience, very pleased this year's influenza epidemic was very much like most years, it was not severe in any sense.
Reminder on what is the influenza virus
Readers of our postings on the influenza virus will be familiar with the nature of the virus. The influenza virus is a specific species of virus that comes in various strains. There is much confusion in the word flu. Flu can mean a cold that is severe, it can mean the stomach flu, it can also mean the influenza virus. To be clear, the influenza virus is a virus that can cause colds, achy respiratory flus, achy fevers, even ear infection and pneuomonias. But in any winter, it is the cause of only about 1/3 of such illnesses. So if you have the "flu" you have a 66% chance of it being caused by another virus, even at the height of the appearance of the influenza virus.
We also know that the influenza virus has a the odd pattern of only causing infections in the United States in the winter, except for rare pandemic forms of it.
Typical patterns of the influenza virus epidemics
Here are the typical patterns the influenza virus causes:
- It typically appears in mid to late December, peaks around New Years Day, and fades in February.
- It changes form slightly every year, so getting it in 2012 offers little protection in 2016.
- Even during its peak times, that is December-February, it causes only about 1/3 of all the colds and flus in the United States.
- It can be very deadly to the frail elderly, but the vast, vast majority of healthy people weather an influenza viral infection safely.
- There are tragic childhood deaths caused by the influenza virus each year in the United States, but the total numbers of these tragedies tend to be in the range of 100 out of millions of infections.
- The influenza vaccine works, even on off years, has reduced the number of deaths from this infection, and helps
This year's epidemic was notable for how typical it was
This year, the media attention to the influenza winter epidemic suggested something very dangerous, ominous, and quite extraordinary was going on. We all were made to feel frightened.
Well, now that the influenza epidemic of 2014-2105 is nearing its end, we can look at the actual data, and guess what, this year's epidemic was in nearly all respects very much like all the others, in a word, it was typical.
- The influenza epidemic of 2014-2015 began right on time in December, and is fading away as most do, right now in February. In fact if you look at week to week incidences, the epidemic tracks remarkable just as the epidemic of 2012-2013.
- The influenza epidemic of 2014-2015, like all other influenza epidemics, featured subtypes the were different from prior years.
- At its peak, which again was around New Years Day, only about 1/3 of the nation's colds and flus were due to the influenza virus.
- Much was made of the tragedy of young life lost to the influenza virus this epidemic, and each such death is indeed beyond understanding, the very definition of tragic loss. But the influenza epidemic of 2014-2015 caused no more child deaths than expected in the United States. As of February 7 the count stands at 80. Last year the count was 109 and the year before 170. This year's influenza epidemic was actually less deadly to children than the last two winter's influenza epidemics.
- The one aspect of this year's epidemic that was notable was that the most prevalent strain was not fully matched in this year's flu vaccines. Even so 50% of those who got the flu vaccine never got infected with the influenza virus this winter.
1. The influenza virus epidemic of 2014-2015 is coming to a close.
2. It was a very typical influenza epidemic.
3. The influenza vaccine, although missing an exact match with one of the prevalent strains, worked once again. The number of childhood deaths from influenza actually dropped, so far this round.
4. With the end of the influenza virus epidemic we are ending administration of influenza vaccine until next season, starting up again sometime around September, well before the time the germ will return, December.
5. Of course, the influenza virus causes very few colds and flus in the spring and summer, but other viruses still do. So, even though the influenza virus epidemic of 2014-2015 is ending, colds and flus will continue.
Dr. Arthur Lavin
Dr. Arthur Lavin
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